Ghost passengers are people who make a booking but do not turn up for the flight. Known in the trade as "no shows", these invisible passengers have serious implications for air travel companies and customers, not least being that genuine travellers are unable to get a seat on their chosen flight. To counter the incidence of ghost travellers and keep fare levels as low as possible, airlines are forced to overbook flights, which can in turn lead to passengers with legitimate reservations being turned away form the flight of their choice.